Feline Constipation

Question 1

functions of the colon

Answer 1

1. fermentation & nutrient production by colonic flora
2. water & electrolyte absorption
3. fecal storage

Question 2

constipation

Answer 2

infrequent, difficult evacuation of dry/hard feces

still productive

Question 3

obstipation

Answer 3

severe constipation resulting in an inability to defecate

NOT productive
requires medical intervention

Question 4

megacolon

Answer 4

irreversible colonic dilation following chronic constipation

muscle fibers come apart and can no longer go back together

Question 5

how is megacolon diagnosed

Answer 5

radiographs

Question 6

idiopathic megacolon

Answer 6

megacolon with no known underlying cause

diagnosis of exclusion

Question 7

dyschezia

Answer 7

difficult and painful defecation

Question 8

tenesmus

Answer 8

feeling of urgency to defecate - manifests as straining

Question 9

predisposing factors for constipation

Answer 9

1. sedentary lifestyle +/- obesity
2. history of trauma
3. dehydration
4. diet - low fiber or high indigestible
5. underlying causes - functional vs mechanical

Question 10

history & PE of constipated patients

Answer 10

history: constipation, tenesmus +/- dyschezia, hematochezia, intermittent diarrhea, hyporexia, weight loss, vomiting

PE:
- distended colon w/ firm feces
- abdominal pain
- +/- dehydration, weight loss, poor BCS, neurologic deficits

Question 11

what to evaluate on a sedated rectal exam

Answer 11

• pelvic fractures
• stenosis
• colonic foreign bodies
• strictures
• masses
• hernias

Question 12

functional etiologies of constipation

Answer 12

systemic underlying cause of decreased motility
1. neurologic
2. dehydration
3. severe electrolyte derangements

Question 13

neurologic constipation

Answer 13

• pelvic trauma
• sacrocaudal luxation (“tail pull”)
• dysautonomia
• ganglionopathy

Question 14

dehydration related constipation

Answer 14

• systemic disease: CKD, diabetes mellitus, chronic vomiting, neoplasia
• lack of access to water/anorexia

Question 15

what electrolyte derangements cause constipation

Answer 15

hypokalemia
hypercalcemia

Question 16

mechanical etiologies of constipation

Answer 16

1. intraluminal - abnormal colon
   - colorectal masses
   - strictures
   - atresia ani
   - foreign bodies
2. extraluminal - normal colon
   - orthopedic stenosis or fractures
   - masses
   - pelvic trauma
   - deformities

Question 17

idiopathic megacolon

Answer 17

most common cause of feline obstipation

cause is unknown - suspected disturbance in colonic smooth muscle contraction leading to chronic constipation –> megacolon

Question 18

diagnostics for functional constipation

Answer 18

1. minimum database
   - CBC: dehydration
   - chem: electrolyte changes or signs of metabolic disease
   - USG: high with dehydration, low with CKD
2. history - trauma?
3. neuro exam
   - decreased anal tone
   - perineal reflex
   - paraparesis

Question 19

diagnostics for mechanical constipation

Answer 19

1. sedated rectal
2. radiographs
3. ultrasound - extraluminal ST masses
4. colonoscopy - intraluminal masses

Question 20

radiographic diagnosis of megacolon

Answer 20

colonic diameter >1.5x width of L5

Question 21

treatment of obstipation

Answer 21

requires HOSPITALIZATION

1. IV fluids
2. serial warm water enemas
3. monitor electrolytes
4. manual deobstipation
   - if medical therapies unsuccessful
   - performed under anesthesia

Question 22

medical management for constipation

Answer 22

must first address underlying causes

1. diet - high fiber
2. stool softeners
3. rectal suppositories
4. cisapride
   - do NOT use metaclopramide - doesn’t work on colon

Question 23

what medical therapies are contraindicated

Answer 23

human enemas - causes severe electrolyte derangements (hypokalemia, hypernatremia)

do not use mineral oil

Question 24

surgical management of obstipation

Answer 24

subtotal colectomy - surgical removal of >95% of the colon

only performed after exhausting all medical options in refractory idiopathic cases